#!/usr/bin/env PyPy

def main():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No")


if __name__ == '__main__':
    main() def main():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No") main x = int(input()) x int(input()) int input() input if x >= 30:
        print("Yes")
    else:
        print("No") x >= 30 x 30 print("Yes") print "Yes" print("No") print "No" if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main def main():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No") def main():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No") main
#!/usr/bin/env PyPy

def main():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No")


if __name__ == '__main__':
    main()
